Electric control system



Dec. 26, 1933. A. J. soRENsl-:N

ELECTRIC CONTROL SYSTEM 1N VENTO/e. Aad/@MJ Jam/wen HIS' A TTORNE Y.

Dec- 26, 1933 A. J. soRENsEN 1,940,736

ELECTRIC CONTROL SYSTEM Filed Aug. 10. 1932 2 Sheets-Sheet 2 HIJ' .4 TTURNE Y.

. uenees.

The v apparatus of 2 1 mitting. an .indication PatentedDec. 26, 1933 o sgrarss i f f refranes l l etioaaro-:ooiwaot .systeem Andrew J, Sorensen, A-lffldgewoorlf Pa.; assignerV to VThe lUnion a.Switch &

Signal Companyfswiss- .valeg a., al. corporation; of l'flennsylvania`' Application ugiistlO, 193%V '..Serial N o. 628,163

' ll Claims.

My invention relates vto electric control systems, and particularly tov electric controlV systems for governing theoperation of railway trains.

[will describe .certain forms of apparatusernbodying .l my invention, and .will then point.. out

vthevnovelY features thereoin claims.

thelaccornpanying drawings, Figsil and, 2

Whenftaken together constituter aidiagrammatic View of one..orrnoapparatus emhoclyingmy invention .when applied to a` communicating. and

Vbrake control system for' a railway train. The .apparatus of'Fg. 1 isthat located at -the control point; which, in this. instance, is onthelocoino- '.tive. The". apparatus ofl Fig. 2-is thatinstalled at another point on .thetraiir While .theapparatus of. Fig; Zmaylbe locatedat anypointon atrain,

it willfbe considered inthis .description asrbeing in lthe Caboose oa freight tra-inf 3;,is a

Heliagrznnnfiatie View. of a. mocliedormof. appa` `ratus that may be used atthe controlpointorat thek second point. on the .train for selectively .receiving the different control and signaling. in-

The apparatus of l is adapted .totransrnit each of several brake .valve and also to transmit at'..tir`nes;slgn`al ing influences. l'urtherrnora-A this .apparatus of f Fig. 1 is capable of receiving indioationjand sig- .naling influences for. causing the display 'o inclicating and signaling devices. )The apparatus of Fig. 2 is adapted toreceive he Vdierent-:control inuences transmitted oy thev apparatus of Fig. lw-for causingnan auxiliary. .brake controlling lmechanismv tov reproduce the functions of .the

usual engineers brake valve von the locomotive.

is. also capable. of transinfluence and Ato receive #andtransrnt signaling influences. .These control, inclication and signaling influences are pre1" erably inthe form or" coded modulated carrier current, i the impulses oik which are. rpreferably f Ytaining a carrier current modulated at alower frequency. VOne method is'toxgenerateaearrier v`frequency*current and aniodulation.frequency currentA separately anrlthen combining thetwo,

while the other-method is to generatetwoldifferent'carrier currents having a frequency diffrequency l .f 70 #..Rererrins mais.. l., .thelensirieersfbrake.irlve EV,is--, o anynfthewel knoyvot-ypes capablepf establishing several AYtrain lorake centro ing kconf ditions; usually release, running., lap, :ser Ce and 'emereencr ...As:..shownschemeiellyi 011- 75 tact. members i and 5 are connected .te and' Ciutedfbyjhehalldl 3. .OUhQblafkQ .YalYeiEV--The ac ontactymembel 4.: adap'd to engagea ogni-@ct `segrnent (iV in;the, seryiceopositiono the handle 3 ;on1y. 'The, contact rnerriher fisladapteclntogen- .30 gagaa centaetsegment 7. inibotht easeand f. running positions, oiihan'dle 3 to engageA a contact..segment 8 in. both' the Elapaldf; I positionsoihanfile '3. '511e functions ogth' tact,assemblytassociated Withfthe brake .ra .Ye EV :sa `will appear as the clescriptioniprogresses. I The :.=loo omotive .is provid d With two coders designatedpby the referencelcharaers-Nl yand *,TNZ. Although. these copiers rnayybe-l any-pnejof many. .types a. preferred` type v,is vrthatA known-asno the mechanicallyytuned Xtype-,such, `for,examp1e,

as isgdi-sclosedin rtheglllnit-erl States-Letters at- .ent, No; .1;858'5876;issuexilillay- 17,H;1932to Raul .N.-Bo.ssart, for Cooling` apparatus, and itihydeemed sufficient jor, the f purpose of this applicatie to -95 describethose eoders only in asgeneralgyvay. Ref errng to coder N1, a.v neldf/ structure J y is proyfiricled;wi-th two pole.; pieces: P1. eldfPZ. between which there. issmounted, l S0: esito Swnsgfreely; i ain-.armature H pivotedat -O-Y The armaiureiH noo i,is;lo iasedtoalmidrpositionpetwee poles` P1 f and'gPZ, that is,-to., the position as shown win Fig; 1.11. In this n 'iicl postionil ontactyginernbeig. 9 actuated `by the .armature` H; fengages l a l contact vl0. A ifield.A Winding 60g is vconneotecltoaehnt L05 source .,suchas abattery -llyby a `s irnple 't @sommari-Fig.. 1. The 1 ene'reiinaoff .the ield rivendica-60: encoder. Nl causes. iits. -.armaturi lf to ,110

4site terminal of battery 11.

" nal of the battery 11.

Vthe operation of the coders N1 and N2.

rotate in a clockwise direction as indicated by an arrow. After a slight movement of the armature H the contact member 9 becomes disengaged from the contact 10 and the eld winding 60 is deenergized. The armature H will rotate a little farther and then due to its bias, will reverse its movement until the contact 10 is again closed and the field winding 60 reenergized. During the movement of the armature H after the contact member 9 disengages the contact 10, the contact member 9 engages a second contact 12. The biasing force and the weight of the armature I-I of coder N1 are made such that it will have a natural period of say sixty cycles per minute, at which frequency it will oscillate as long as current is supplied to its field winding 60 by the circuit that includes its own contact member 9. It follows, that the contact member 9 of coder N1 will be oscillated between the two contacts 10 and 12 at the code frequency of sixty cycles per minute. The coder N2 is similar to coder N1 except that its biasing force and the weight of its armature are made such that it has a natural period of say one hundred cycles per minute at which frequency its contact member 13 will be oscillated between the two contacts 14 and 15 as long as its eld winding is supplied with current from the battery 11 by the circuit that includes its own contact member 13 and the contact 14.

Associated with these two coders N1 and N2 is a relay 16 which is supplied with current from the battery 11 by any one of three separate circuits. A first circuit for the relay 16 can be traced from the battery 11 through winding of relay 16, the upper and normally closed Contact 17 of a manually operated signaling key K1, contact 12 of coder N1, contact member 9 and back to the opposite terminal of battery 11. With the signaling key K1 depressed to bring the contact member 17 to the position indicated by dotted lines in the drawings, a second circuit for relay 16 can be traced from battery 11 through winding of relay 16, contact member 17, contact 15 of coder N2 and contact member 13 to the oppo- When the handle 3 of the brake valve EV is moved to the service po- 4sition so as to bring the contact member 4 into engagement with the contact segment 6, a third circuit for relay 16 can be traced from battery 11 through winding of relay 16, contact member 4, contact segment 6, and to the opposite termi- It follows, that with the signaling key K1 in its upper and normal position the relay 16 is energized once each cycle of thecoder N1 thereby causing its armature 84 to be operated between its front contact 18 and its back contact 19 at the code frequency of sixty cycles per minute. When the signaling key K1 is depressed, the relay 16 will be energized once each cycle of the coder N2 causing its armature 84 to be operated at the code frequency of one hundred cycles per minute. When'the hande 3 is moved to the service. position, the relay 16 will be held steadily energized irrespective of With relay 16 operated in step with either of the coders N1 or N2 its front Contact 18 is closed approximately one half of the time and its back Contact V19 is closed approximately one half of the time. 'As will shortly appear the relay 16 when thus operated divides the time into transmitting and receiving periods by the closing of a transmitting circuit at its front contact 18 and .by the closing of a receiving circuit at its back contact 19.

Thus with the engineers brake valve EV in any of its operating positions, except the service position, and the signaling key K1 in its upper and normal position, the locomotive apparatus alternates between the transmitting and the receiving conditions at the code rate of sixty times per minute, and with the signaling key Kl depressed, it alternates between the two conditions at the code rate of one hundred times per minute, while, when the handle 3 of the brake Valve EV is moved to the service position, the locomotive apparatus is'held steadily in the transmitting condition only.

20 and 21 are inductor coils located on the locomotive in inductive relation with the traffic rails 1 and 1a, respectively. By means of these inductor coils 20 and 21 energy is transmitted to and received from the traffic rails by the locomotive apparatus, and to this end they are alternately connected to the transmitting circuit and the receiving circuit by the operation of the relay 16 as will shortly appear.

On the locomotive there are provided three generators G, G1 and G2 adapted to supply carrier current at different frequencies such, for example, as two thousand, two thousand twenty, and two thousand thirty cycles per second, respectively. Since the specific type of these generators forms no part of my invention, they are shown conventionally only in the drawings. The symbol G indicates apparatus by means of which current of a carrier frequency of two thousand can be obtained, and likewise symbols G1 and G2 indicate apparatus by means of which current of the carrier frequencies of two thousand twenty, and two thousand thirty, respectively, can be obtained. The output of these generators is delivered to a power amplifier PA. The output oi' generator G is connected directly to the input of the power amplier. The output of generator G1 is connected to the input of the amplincr over wire 22, contact segment 8, contact member 5 when handle 3 occupies either the lap or the service position, wire 23, power amplier PA and wire 24 to the other output terminal of generator G1. The output of generator G2 is connected to the input of power amplifier PA over wire 25, contact segment 7, contact member 5 when handle 3 occupies either the release or the running position,wire 23, power amplifier PA, and wires 24 and 26 to the opposite terminal of generator G2. The power amplier PA amplies the current received from the generators G, G1 and G2 and delivers it to the inductor coils 20 and 21 over the transmitting circuit. This transmitting circuit can be traced from the rightj? hand output terminal of power amplifier PA through wire 27, coils 21 and 20 in series, wire 28, armature 84 of relay 16, front Contact 18 and wire 29 to the left-hand output terminal of power amplifier PA. Thus, with the handle 3 of the brake valve EV moved to either the release or the running position the coils 20 and 21 are supplied, each time the relay 15 is energized to close its front contact 18, with an impulse oi carrier current of the combined frequencies oi two thousand and two thousand thirty which produces the effect of a carrier frequency of two thousand modulated at thirty cycles. When the handle 3 occupies either the lap `of the service position, an impulse of carrier current of 'the combined frequencies of two thousand and two thousand twenty, producing the effect of a carrier current of the frequency of two thousand modulated at twenty cycles, is supplied to the coils 20 and 21 each time the relay 16 is picked r sandlrand twoythousand twentygproducingathef imanes' up. Whenltheihandle 3occupiesgtherseryice position :the .relay 31.6 :is 'held steadilyienergized, .coils .20 :ar1d2l' :are.continuously `supplied with currentof the -icjombinedirequencieso ;tvvo1thou eiTect of .ai continuous impulse fof carrier current-foi the frequency "oi tvvo thousandtm'odulat ed: at `twenty :.cycles. When thehandle .13 :occupies itheeinergency position, ztheeinipulsesssupyplied 'to VVthe lcoils `2li and 2l containazthe single carrier frequency oftwo thousandgiving the eflectofa :nonsmodulated jcarrier current-Of the frequencylof twolthousand. JThe .codeirequency of zthe 'impulses 'supplied tothe coils w20 andl2l will befsixty Lper ,minute when fthe signalinf :key R21-occupies .its Aupper fand: normal position icausing the `coder'Nl to beactive .and the v'coole-trequency r-Will be one hundred per rrifiinute when the signaling key Kl isdepressed .causing .the

ooder;N2 to JoeactiVe.` V"Asstatedabove, Ivvhenthe handle i3 foccupies vtheseiyice position, .the l1relayilrlis held steadily energized and thus 'the I Ycurrent''supplied to the coils 2G and2l inoncoded. The .power .amplifier PA `maybe anyone .of a number of types.. dong theni being :the vacuum tube type. As' tnerspecioitype of this powerzarnplierformsno part oirny invention, it is shown conventionally onlyinfordertosimpliiy the drawings. It will be understood-that myfin .vention is not Vlimited to the .frequencies of. two thousandtwothousand"twenty, and two .thousand .thirty or the carrier currents, nor tothe codezfrequencies of sixty Lando-ne hundred,.and that these frequencies are given by .Wa-y of illus-r tration `only as other frequencies could equally -Well fbei selected should it seein vdesirable to do so.

Referring to Fig. .2, 3l) .and 31 .ar-e inductor coils similar .to the coils..2 G .and21, and kthese coils and glare-:mounted at the Caboose in i. inductiverelation-With the trahie rails 1 and Ile,

respectively. v'.ihexinductor Acoils .30 and Blare connected `either to a receiving circuity or .to .a transmitting `.circuit of'Fig.' 2 the 'following manner. With the apparatus of Fig. 2 alldeenergized the coils 3 31 arev connected .to the receiving circuit Whichcan be tracediirom'the right-hand terminalof coils 30 .and 3l through wire 32, input side Yoa filter Fl to be referred tolater, WireA V33, yioaclr Contact 34 rof a relay 35y i to he described later and Wire 36 tothe rleft-hand terminal of coils 30 and 3l. Under conditions to be vdescribed later this receiving `circuit is` at times-completed by the paththat branches from Wire33 through the front rContact 37 of a relay 38'to -be 'referred-,tolateig and thence by the Wire 36 'to the let-hand terminal of coils 30 and 31. Under the condition of re1ay-35 .being picked up to close front contact 39 and the relay 38..being deenergize to close its back contactlfas Will appear when the operation of the system is-descriloed, the coils 30 and 3l are -con nected to thetransrnitting circuit, which can be traced from the .right-hand terminal of the coils along-Wires 32 and 4l, outputfof -a lpower amplilier PA, .vire 42, front` contact 39 Vof relay 35, back contact 40 of relay 38 and thence `by the Wire 36 to the left-hand terminal ofthe coils 30 andl. e l

.The filter lFl isa band pass filter .of-any one of 4.several .well-known types and is so proportioned .and adjusted as yto Ypass current of the range ofthefrequences of. generators G, Gl .and G2 on QtheY locomotive, vto theinput of -an ampli'- erAM withrelativdy low attenuation but offer-Lv ing a relatively. high. attenuaticnto .frequencies -twoithousan''dthirtyv cycles penseoond Theiam'- are .shown conventionally :onlyfin the rlravvings.

.Partiofithezoutput current delivered bythe: amplifier is fed to a relay .43 .throughaiull Wave rectiier 45. This :circuit .being :non-'tuned the relay 43 Will, therefore, respond-.to :anyfmodulationfrequency appearing-.inthe :outputxof lampliiier AM. .The remainder of fthe routput @of ithe varnplier AMiiszapplied toa relay V46 throughmd The highfpass i1ter12 may besef different'type but .preferably `is-:of .the -form lincluding condensers 44, 44a and 4ibiiin .series.and...inductances L93v and 93e in shunt Wlththe circuitiin the-usualmanner. The parts 'of 'this lilter are .so lproportionedand adjustedxas to passcurrent of alfrequency .above twenty-'five 'cycles per..secondand tosubstantially prevent theipassagefor .all .current 'belowthe' lou*- off .frequency .of `*twenty-five cycles `,per second. `From :Whathas "just .been said, it. is vclear that relay 14S will be energized .when theoutput-'current'offampliler Alvlcontainsthe modulation frequency. of thirty .cycles perrsecond but"vvillnotA be energized whenthe modulation. isz twentyfcycles per .second That y.is to `say, relay 43 YWill be operated in response vtohcode impulsesof Ycarrier* current appliedvto'the input oftheamplier AM when themodulation -frequency is .either twenty or thirty cyclesper second, loutthe relay 146 will be v.operated only when .the carrier current -is modulated iat a frequencyabove .the cut-off ifrequency of the high pass filter F2,.Which in this instance is twentyeve cycles per second.

a simple `circuit for energizing the relay 538, and therelay 46 controls overits frontfcontact 49 .a simple circuit for energizing a'relayias YWillbe readily .understood by an .inspection .of Fig. l2. Thus with code impulses oiimodulatedfcarrier current picked up from the traino rails l and Ilfby the coils 30 and Sltherelay 43, and in turn .the relay 3S,-Will he :operated at the code :frequency of the impulses. Whentheimodulation frequency is above thev cut-01T frequency 'otwenty-five cycles per-second, the relay46 'Willfalso besoperated to-energize the relay fvvhich is slow-releasing :in 'character and .willthus remain picked up from one code impulse to the next.

YOperating the relay 381causes current'to bealternately suppled to the two halves of kthe primary Winding 51 of a transformer T, thercircuit being completed from the terminal B of the cur.- rent sourcezthroughy the .top half of the Winding 51yand to the terminal C of the current-source, when the iront Contact 52 'of 'relay 38 .is closed, and completed through'thebottomhalf ofnthe primary'l VWhen the back contact 53 ris closed. This .alternate energizing of the ytwoy halves .of

primary 5l or" transformer T induces :an valterhating voltage in the secondary windingsfl and 56 is slow-releasing in character and will thus -retain its front contacts 58 and 59 closed whenever the relay 38 is operated at either vthe code frequency of sixty or one hundred per minute but will be released when relay 38 is held steadily energized or when it is deenergized for any length of time. The circuit for the secondary 54 includes a condenser 62 and a reactor 61 in series. A portion of reactor 61 is connected to the winding of a relay 63 through a full wave rectifier 64. The parts of this circuit supplied by the secondary 54 are so proportioned and adjusted that the relay 63 is energized when the relay 38 is operated at the code frequency of one hundred cycles per minute only.

The relay 38 controls over its front contact 65 a simple circuit for energizing the relay 35. As previously pointed out, the receiving circuit is completed through either the front contact 37 of relay 38 or the back contact 34 of relay 35 and the transmitting circuit for the apparatus of Fig. 2 is completed through the front contact 39 of relay and back contact 40 of relay 38 in series. Thus when an impulse of modulated carrier current is picked up by the coils 30 and 3l to operate the relay 43, and, in turn, the relay 38, the receiving circuit is held closed at the front contact 37 as long as the impulse lasts. At the termination of such incoming impulse, the relay 38 immediately drops to close its back contact but relay 35 remains picked up for a period as it is slow-releasing in character, and thus during its release period, the inductor coils 30 and 31 are connected to the transmitting circuit described hereinbefore. At the end of kits release period, the relay 35 drops to open the transmitting circuit at its front lcontact 39 and to again close the receiving circuit at its back contact 34. It will be understood that the release period of relay 35 is made less than one-half cycle of either coder Nl or N2 on the locomotive. It follows that the receiving circuit of Fig. 2 is closed at all times except for a period immediately following the termination of an incoming impulse of modulated carrier current, at which time the transmitting circuit is closed during the release period of the relay 35 which period in any event is less than one-ha1f cycle of the active coder on the locomotive. -r

The caboose is equipped with an auxiliary brake controlling mechanism which includes a main reservoir MR, a feed valve FV and three electropneumatic valves DR, DE and DS. The caboose, of course, will also be equipped with a compressor, air gages and all other equipment necessary to insure ample supply of air pressure in its main reservoir MR independently of the usual supply of air pressure on the locomotive. The Valves DR and DS are biased to the closed position and are lifted to the open position when the associated magnets 68 and 69, respectively, are energized. The valve DE is biased to the open position and is held closed when its associated magnet 70 is energized. When valve DR is open, due to its magnet 68 being energized, the main reservoir MR is connected to the train brake pipe, indicated by the reference character BP, through the feed valve FV, and the auxiliary brake controlling mechanism in the caboose reproduces the running condition of the engineers brake valve EV on `the locomotive. When the valve DS is open, due to its magnet 69 being energized, the train brake pipe BP is connected to the atmosphere through a vent of such characteristics as to effect the service application of the train brakes. When the valve DE is open, due to its magnet 73 being deenergized,' the brake pipe BP is connected to the atmosphere through a vent of such characteristics as to eifect an emergency application of the brakes.Y When the valve DE is held closed, due to its magnet 70 being energized, and both valves DR and DS are closed, due to their respective magnets being deenergized, the supply and the exhaust of the brake pipe BP are both blanked and the auxiliary brake controlling mechanism reproduces the lap condition of the engineers brake valve EV. In the form of apparatus shown in Fig. 2, the magnet for the emergency valve DE is the one normally held energized to insure the closed circuit principle for my system. 1t will be understood, however, that the magnet of either of the other two valves could be so employed should it seem desirable to do so.

Whenever both relays 56 and 50 are picked up in a manner to appear later, current is supplied to the magnet 63 of valve DR by a circuit which extends from the terminal B of the current source through winding of magnet 68, wire 71, front contact 72 of relay 50, front contact 58 of relay 56 and to the opposite terminal C of the source of current. With relay picked up, the magnet 70 of valve DE is supplied with current from the terminal B of the current source throughV winding of the magnet and the front contact 59 of relay 56 to the terminal C of the current source. In the event the relay 35 is held steadily energized and both relays 50 and 56 are deenergized, the magnet 69 of valve DS will be energized by current flowing from the terminal B of the current source through winding of magnet 69, back contacts 73 and 74 of relays 56 and 56, respectively, and front contact 66 of relay 35 to the terminal C, to open the valve DS. At such a time, that is, when relay 35 is held steadily energized, the magnet 70 of valve DE will be energized by the circuit that includes the front contact 67 of relay 35. The caboose is provided with a signaling device 75 the function of which will appear later, and which may be either a lamp or a magnet. The signaling device 75 is provided with a circuit that extends from the terminal B of the current source through the lamp 75 and the front contact 76 of relay 63 to the opposite terminal C.

As stated earlier in the specication, the caboose apparatus is adapted to at times transmit an indication influence. t has been pointed out in detail hereinbefore how the coils 3o and 31 on the caboose are connected to a transmitting circuit which includes the output of the power amplifier PA, during the release period of relay 35 immediately following the termination of an incoming impulse. The caboose is provided with three generators of carrier frequency current G, G1 and G2. These generators are preferably similar to the corresponding generators on the locomotive. That is to say, generator G of Fig. 2 delivers carrier current of the frequency of two thousand cycles per second, generator G1 delivers carrier current at the frequency of two thousand twenty, and generator G2 at the frequency of two thousand thirty. The power amplifier PA of Fig. 2 is also preferably similar to the power amplifier PA of Fig. 1 and this power amplier in the caboose receives the current from the generators G, G1 and G2 and delivers it to the coils 30 and 3l through the transmitting circuit. The output of the generator G is applied directly to the input of the power amplifier PA, while the Cycles and thus when picked up by the coils 20 and 21 on the locomotive and applied to the input of the amplier AM through the band pass filter El causes the relay 86 to be energized but will not affect the relay 89 due to the high pass filter F2. With relay 86 energized the indication lamp 88 is displayed to the locomotive operator to indicate that the auxiliary brake controlling mechanism in the Caboose has responded to the running code impulse transmitted from the locomotive. As long as the handle 3 of the brake valve EV remains in the running position there will be alternately exchanged between the lecomotive and the Caboose apparatus impulses of modulated carrier current to hold the auxiliary brake controlling mechanism in the running position and to display the indication lamp 88 on the locomotive.

I will next assume that the handle 3 of the brake valve EV is moved to the lap position where the contact member 5 engages the contact segment 8 and the input of the power amplifier PA of Fig. 1 is made to contain carrier current of the two frequencies two thousand and. two thousand twenty giving in effect a carrier current of the frequency of two thousand modulated at twenty cycles. The signaling key K1 ystill remaining in its upper and normal position, code impulses of current having the effect of a carrier current of the frequency of two thousand modulated at twenty cycles will be now transmitted from the locomotive each time the relay 16 is picked up. At the Caboose, the receipt of an impulse of carrier current modulated at twenty cycles Causes the relay 43 in the output of the amplifier AM to be operated the same as described under the running condition, but the relay 46 will be'now deenergized due to the high pass filter F2 preventing the passage of the modulation frequency of twenty cycles and the relay 50 will be in turn released. Operating the relay 43 causes the relays 38 and 35 to be operated in the same manner as hereinbefore described to transfer the Caboose apparatus between the receiving and transmitting conditions in step with the locomotive apparatus, and also to retain the relay 56 picked up. As relay 50 releases, the magnet 68 is deprived of current and valve DR will be closed. Relay 56 still being picked up, the magnet 70 of the valve DE is retained energized to hold valve DE closed. Thus, all three valves DR, DE and DS of the auxiliary mechanism are now Closed and the auxiliary mechanism reproduces the lap condition established by the valve EV on the locomotive. Contact 80 still being held closed, impulses containing both the carrier frequencies two thousand and two thousand twenty, giving the effect of a carrier current of the frequency of two thousand modulated at twenty cycles, are still transmitted from the Caboose, which cause the indication lamp 88 on the locomotive to be displayed in the same manner as pointed out under the running condition of the brake valve EV. Thus as long as the handle 3 is retained at the lap position, impulses are exchanged between the locomotive and the Caboose apparatus at the code frequency of sixty cycles per minute, the impulses transmitted from the locomotive containing the two carrier frequencies of two thousand and two thousand twenty and the impulses returned from the caboose to the locomotive also containing the two frequencies two thousand and two thousand twenty. The exchange of these impulses cause the auxiliary brake controlling mechanism to be held in the lap position and the indication lamp 88 to be displayed.

In the event the handle 3 of valve EV is moved to the service position, Contact member 5 still engages the Contact segment 8 and the input of the power amplifier PA of Fig. 1 contains both the carrier frequencies two thousand and two thousand twenty the same as under the lap position of handle 3. The Contact member 4, however, now engages the' contact segment 6 and the relay 16 is held steadily energized and the transmitting circuit held Continuously closed so that there is now continuously transmitted from the locomotive current having the ei'fcct of a carrier Current of the frequency of two thousand modulated at twenty cycles. At the Caboose, the continuous receipt of energy in the form of a carrier Current of the frequency of two thousand modulated at twenty Cycles causes the relays 43, 38 and 35 to be held continuously energized and the relays 46, 56, 63 and 5G all to be deenergized. The magnet 70 of valve DE is now controlled by the circuit Vthat includes the front Contact 67 of relay 35 and the magnet 69 of valve DS is supplied with Current over the back contacts 73 and 74 of relays 50 and 56, respectively, and the front contact 66 of relay 35. With valves DR and DE beth closed and vvalve DS o-pened'the auxiliary brake Controlling mechanism establishes a service application of the train brakes; Tr e transmitting circuit fo-r the Caboose apparatus is now held continuously open due to both relays 38 and 35 being held continuously encre.

gized andthus no return impulses are transmitted to the locomotive apparatus and the relay 86 is released to extinguish theindication lamp 88.

With the handle 3 of valve EV moved to the emergency position, the relay 16 is operated at the code frequency of cycles per minute but only generator G is new active to supply carrier current to the input of the power amplier PA and the impulses transmitted from the locomotive apparatus are non-modulated Current of the frequency of two thousand, with Vthe result that neither relay 43 ner relay 46 of the Caboose 'apparatus is energized. The deenergized condition of both relays 43 and 46 cause in turn the relays 38, 3.5, 56, 63 and 50 to all become deenergized and the magnets 68, 69 and 70 all to be deprived of current.` Deenergizing magnet 70Y permits the valve DE to be opened and the auxiliary brake controlling mechanism to j produce an emergency application of the train brakes. Relays 38 and 35 not now being operated no return impulses are transmitted from the Caboose and thus both relays 86 and 89 on the locomotive are deenergized.

Under the running and the lap positions of the valve EV the operator on the locomotive can signal to the crew on the Caboose by depressing the signaling key K1 for long or short intervals in accordance with a prearranged ccde. The depressing of the signaling key Kl Ycauses the relay 16 to be operated in step with the coder N2, that is, the code frequency of the code im- L cut-off frequency, and means to impress the con?- bined currents upon the electroresponsive means whereby the auxiliary mechanism is made to register with the position of the engineers brake valve.

4. A control system for railway trains including, an electroresponsive means on the train selectively responsive to different modulation frequencies of an alternating current, a first output circuit for said electroresponsive means including a high pass lter having a predetermined cutoff frequency, a first relay controlled by said first output circuit, a second output circuit for said electroresponsive means not including a filter, a second relay controlled by said second output circuit, control means having one position for supplying alternating current modulated at a frequency above said predetermined cutoff frequency and a second position for supplying alternating current modulated at a frequency below said cutoff frequency, means for impressing the current from said control means upon said electroresponsive means whereby said nrst and second relays are selectively controlled, and a controlling mechanism jointly controlled by said relays.

5. A control system for railway trains including, current sources at one point on a train adapted to supply alternatin.L7 current modulated at a first or a second modulation frequency, an electroresponsive means at another point on the train responsive to modulated alternating current, a relay, an output circuit for said electroresponsive means for controlling said relay and which includes a high pass filter having a cut-oli" frequency between said first and second modulation frequencies whereby current is passed to said relay in response to alternating current of the second modulation frequency only, a controlling mechanism governed by said relay, and means to at times impress current from said sources modulated at said second modulation frequency upon the electroresponsive means for governing said controlling mechanism.

lt. A control system including, a first and second station interconnected by a communicating circuit, three generators of carrier current of different frequencies at each station, manually controlled means at the first station to combine the output of different pairs of its generators to form a first or a second frequency difference, transmitting means at the first station to periodically supply said combined output to the circuit, a deincdulating means at the second station periodically connected with the circuit to receive and demodulate the current supplied at the first station, a first ouput circuit for the demodulator including a filter having a cut-of.F frequency midway between said iirst and second frequency difference, a second output circuit for said demodulator and non-tuned, an operating mechanism controlled by said output circuits, means governed in part by the operating mechanism to combine the output of different pairs of the generators at said second station to form a first and a second frequency difference, transmitting means at the second station to periodically supply the combined output of generators to the communicating circuit, a receiving and demodulating means at the first station periodically connected with the communieating circuit to receive and demodulate the current supplied at the second station, a first output circuit for said deniodulator including a filter having a cut-off frequency midway between the two frequency differences of the second station. a second output circuit for said demodulator and non-tuned, indicating means at the first station controlled by its output circuits, and synchronizing means for governing the transmitting and receiving means at each station whereby a continuous two way control is obtained between the two stations. 'l'. A control system including, a first and a second station interconnected by a communicating circuit, three generators of carrier current of different frequencies at the nrst station; manually controlled means at the first station having a first position to combine and code the output of a particular pair of the generators to form a first coded frequency difference, a second position to combine and code the output of a different pair of the generators to form a second coded frequency difference and a third position to combine only the output of the last mentioned pair of generators to form a non-coded frequency diiference; means at the rst station to supply said output of the generators to said circuit, receiving and demodulating means at the second station connected with' said circuit, a rst output circuit for the demodulator and including a filter having a cut-off frequency midway between said first and second frequency differences, a relay controlled by said output circuit, a second output circuit for said demodulator and non-tuned, decoding means controlled by said second output circuit, and operating mechanism having three different positions and selectively controlled by said relay and said decoding means to cause said mechanism to registe-r with the position of the manually controlled means.

8. A control system including, a iirst and a second station interconnected by a communicating circuit, three generators of carrier current of different frequencies at the first station, manually controlled means to combine the output of a particular pair of the generators to form a first frequency difference and a second position to combine the output of a different pair of the generators to form a second frequency difference, means at the first station to supply said output of the generators to said circuit, receiving l and demodulating means at connected with the circuit, a first and a second control relay, a non-tuned output circuit receiving current from the demodulator for controlling one of the relays, a tuned circuit receiving current from the demodulator for controlling the'other of said relays and including a filter the second station having a cut-off frequency midway between saidv frequency differences whereby relatively large variations of the frequency differences may be tolerated without a loss of control.

9. Apparatus for the control of train brakes comprising in combination with the usual engineers brake valve on the locomotive, an auxiliary brake controlling mechanism at another point on the train capable of reproducing different conditionsof the engineers brake valve,` three generators of carrier current of different frequencies on the locomotive, means governed by one position of the engineers brake valve for combining the output of a particular pair of said generators to form a rst frequency-difference, means governed by a second position of the engineers brake valve for combining the output of a different pair of the generators to form a second frequency difference, means for supplying the output of said generator to the traffic rails, receiving and demodulating means at said other point and inductively coupled with the trafc rails to receive the current transmitted ifi@ ' from the locomotive, a pair ofcontrol relays, a

' point on the train non-tuned circuit receiving current from the demodulator to control one relay,

a tuned circuit receiving current from the demodulator to control the other relay and including a filter having a cut-01T frequency midway between said frequency differences, and means controlled by said relays for causing the auxiliary mechanism to register with the engineers brake valve.

10. Apparatus for the control of train brakes comprising in combination with the usual engineers brake valve on the locomotive, an auxiliary brake controlling mechanism at another capable of reproducing different conditions of the engineers brake valve,

vthree generators of carrier current of different frequencies on the locomotive; means governed by one position of the brake valve to combine and code the output of a particular pair of said generators to form a first coded frequency difference, by a second position to combine and code the output of a diierentpair of the generators to form a second coded frequency difference and by a third position to combine only the output of the last mentioned pair of lgenerators to form a non-coded frequency difference; means for supplying the output of said generators to the traiiic rails, receiving and demodulating means at said other point and inductively coupled with the trafc rails to receive the currenttransmitted from the locomotive, a decoding'means, a nontuned circuit receiving current from the demodulator to operate the decoding means, a first relay controlled by the decoding means, a tuned circui receiving current from the demodulator and including a filter having a cut-off frequency midway between said frequency differences, a second relay controlled by the tuned circuit, and means selectively governed by said relays for causing the auxiliary mechanism to register with said engineers brake valve.

VV11. Apparatus for the control of train brakes comprising in combination with the usual engineers brake valve on the locomotive, an auxiliary brake controlling mechanism at another pointon the train capable of lreproducing a given conditionof the engineers brake valve, two generators of carrier current of different frequencies on the locomotive, means governed by the given position of said brake valve to combine the output of said generators to form a given frequency difference, transmitting means to periodically supply the output of said generators to the traflc rails, receiving and demodulating means at said other point and periodically vcoupled with the traflic rails toreceive the current transmitted from the locomotive, a circuit receiving current from the demodulator and including a filter having a cut-off frequency above said frequency difference, means controlled by said circuit for causing the auxiliary mechanism to establish said given position,l a pair of generators of carrier current of different frequencies at said other point, means controlledl by the auxiliary mechanism for combining the output of said pair of generators to form an indication frequency difference, means to periodically supply the output of said pair of generators to the traiiic rails, receiving and demodulating means at the locomotive periodically coupled with the trafc rails to receive the current transmitted from said other point, a circuit receiving current from the last ANDREW J. soRENsEN. 

